The year was 1949. Dr. William
Bigelow and Dr. John Callaghan at the Banting and Best Institute laboratory in Toronto
were studying how extreme cold could slow the human heart rate thus making it possible to
conduct open heart surgery. Although their work had led to a number of successful open
heart surgeries, they were stuck on the problem of how to re-start the heart if it were to
stop.

The Pacemaker -- Helping millions of people
lead normal, healthy lives! (Corbis)

Enter Dr. John Hopps, electrical
engineer and National Research Council researcher. Working with the two physicians, John
Hopps, P. Eng. and his team found that applying a gentle electrical stimulus to the heart
would not only duplicate the normal body nerve stimulation but it would also not cause any
harm to the heart muscle. In addition, this technique would start a stopped heart and
increase or decrease the heart rate, as required.

The
first pacemaker was developed in 1950. It was large (about 30 cm long, and several
centimetres high and wide), the pulses were generated by vacuum tubes and the entire unit
was powered by 60 Hz household current. Its size meant that it wasn't of immediate
practical use but with the advent of transistors and reliable batteries, the package grew
smaller until a pacemaker was successfully implanted in the chest of a Swedish man in
1957. They have since become a common medical tool.